Lens implant

ABSTRACT

The lens implant serves to replace the lens body of an eye and possesses substantially the same size and shape. It is elastic such that the eye gets back its capability for accommodation. It consists of two parts ( 10, 11 ) with differing refractive indices and/or differing shapes, which allows to adapt the focal length and shape to specific requirements in simple manner. A distal part ( 11 ) is prefabricated as pre-made lens part, while the proximal part ( 10 ) can preferably be brought into the lens capsule in a flowable state.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the priority of Swiss patent application No. 0212/00, which has been filed on Feb. 3, 2000 and of which the entire enclosure is included herein by reference.

BACKGROUND

[0002] The invention relates to a lens implant and a kit and a method for producing a lens implant in accordance with the preamble of the independent claims.

[0003] A lens implant of this kind is known e.g. from U.S. Pat. No. 4.608.050 or WO 89/00029. It consists of a flexible body which replaces the lens body of the eye. Its shape and size correspond substantially to the one of the typical lens body. Due to its flexibility it allows an good accommodation of the eye.

[0004] In order to adjust this lens implant to the individual requirements of an eye, a plurality of implant bodies with various different refractive indices must be may available. This necessitates large expenditures. It has been found, furthermore, that the implant bodies meet the requirements regarding stability and simultaneous accommodation properties in a limited manner only.

[0005] FR 2.698.264 describes a lens consisting of two partial lenses between which a filler mass is arranged. The part lenses form the outer shape of the lens and replace the lens capsule. Because to this connecting the lens to the ocular accommodation mechanism becomes difficult. Furthermore, the mechanical properties of the lens are quite different from the ones of a natural lens which renders the accommodation more difficult.

[0006] In U.S. Pat. No. 5.275.623 a lens implant is disclosed which consists of a bag with two lenses. The bag is filled by a gas or a liquid. Due its symmetry, however, this lens features properties that basically deviate from the ones of a natural lens so that it hardly can be satisfactory in practice.

PRESENTATION OF THE INVENTION

[0007] Thus, there is the object to provide a lens implant and a kit and a method, respectively of the kind mentioned above which avoid these drawbacks.

[0008] This object is met by the lens and the kit and the method, respectively, in accordance with the independent claims.

[0009] The lens implant according to the invention consists thus of a first deformable part and a second part, wherein the two parts have different refractive index and/or different elastic deformability. The first part forms the proximal portion and the second part a distal portion of the lens implant.

[0010] Accordingly, the implant can be set together of two differing parts which allows to adjust the focal distance and/or the mechanical properties to suit the respective requirements in a simple way. Thus, the first part can e.g. basically define the size and the volume, respectively, of the lens and ensure the accommodation while by choosing the second part the focal distance and/or the distal shape can be set.

[0011] The implant has essentially the shape of the lens body to be replaced so that it fits into the lens capsule and fills same properly. To this end the distal surface of the implant should have a stronger curvature than the proximal surface.

[0012] The first part consists preferably of a material which is cureable intraoccularly from a flowable to an elastically deformable state so that it can be made to adapt to the shape of the lens body replaced in a simple way.

[0013] For a good accommodating capability the first part should be better elastically deformable than the second part, specifically if latter defines the distal surface of the lens implant.

[0014] The second part can be designed elastically deformable, suitable for a introduction into the lens capsule in a rolled up or folded state. This is specifically advantageous in combination with a cureable first part, because the first part can be used in this case for a filling the lens capsule and guarantees accommodation capability, while the focal distance of the lens implant is given by the second part.

[0015] Preferably, the second part forms the distal portion of the lens implant so that it forms a wall which separates the first part from the distal part of the lens capsule. This allows to remove, if necessary, the distal part of the lens capsule if such should become opaque.

[0016] The kit for the production of such lenses includes preferably at least one flowable filling material and a plurality of pre-shaped lens parts for the forming the second part. The lens parts feature various different shapes and/or refractive indices. Thus, it is possible to produce with only one single filling material a plurality of lens implants of various differing focal distances and shapes.

SHORT DESCRIPTION OF THE DRAWINGS

[0017] Further embodiments, advantages and applications of the invention follow from the dependent claims and the now following description with reference to the drawings. It is shown in:

[0018]FIG. 1 a section through a normal eye,

[0019]FIG. 2 a section through an eye with lens implant,

[0020]FIG. 3 a possible production method for the lens implant and

[0021]FIG. 4 a section through an eye with an alternative embodiment of the lens implant.

WAYS FOR EMBODYING THE INVENTION

[0022] The part of the eye that are the most important ones in the present context are illustrated in FIG. 1 and include the lens 1, consisting of a lens capsule 2 and a lens body 3, the iris and the cornea 5.

[0023] The lens 1 is an elastic body of which the curvature changes upon a contraction of Müller's muscle 6, so that an accommodation of the eye to various focal distances becomes possible. With increasing age, however, the lens body 3 becomes harder, which leads to a partial or complete loss of the accommodation property.

[0024] The present invention relates to a lens implant which replaces the lens body 3 of the eye. Such a lens is illustrated in FIG. 2. It consists of two transparent parts 10, 11 which abut against each other and which together have about the same size and shape as the replaced lens body 3 accommodated to infinity. Thus, the distal surface 12 a of the lens implant is curved stronger than the proximal surface 12 b as is the case at the lens body. The term proximal denotes, in this context, the lens side facing the cornea, the term distal the lens side facing the retina.

[0025] The lens implant has the same size and shape as a natural lens body when it has a convex proximal surface with a radius of curvature between 8.4 and 13.8 mm, a convex distal surface with a radius of curvature between 4.6 and 7.5 mm and a thickness between 2.8 and 5.5 mm. The typical equator amounts for eyes of grownups to about 9 to 11 mm. Typical proximal and distal radii of curvature are 10 and 6 mm, respectively.

[0026] The lens implant, i.e. specifically its first part, features optical and elastic properties which are similar to those of a lens body with a good accommodation capability. It is usually enclosed tightly by the lens capsule 2 and generates, just as a natural lens body, a intracapsulate pressure. Upon contraction of the Müller's muscle 6 the curvature of the surfaces of the lens implant, and accordingly its focal width, changes. Thus, the lens implant gives a natural accommodation capability to the eye. To this end the volume of the first part 10 should be larger than the one of the second part. Preferably also the total diameter perpendicular to the axis should be larger at the first part than at the second part.

[0027] The two parts 10, 11 of the lens implant preferably feature refractive indices that differ from each other. During the production of the lens the first, proximal part 10 is made to suit the size and shape of the lens body 3 to be replaced whereas the second, distal part 11 is a prefabricated, elastic, shaped body.

[0028] When producing the lens the two parts 10, 11 fulfil different objects. The proximal part 10 defines the volume of the lens. The distal part 11 renders stability to the rear lens portion and allows to adjust the focal distance to the respective eye individually. To this end a kit is available for the person skilled in the art for producing the lens which includes the flowable filling material and a plurality of pre-fabricated lens parts. The lens parts differ from each other in their refractive index and/or their shape.

[0029] The lens implant is produced by bringing together the flowable filling material and one of the lens parts and the filling material is cured to the desired rigidity. This can proceed outside of the eye or intraoccularly. Hereto, the eye is initially measured in order to determine the focal distance and the shape of the lens body and, respectively, in order to determine from the properties of the eye the desired refractive index of the implant. From this it can be calculated which of the available lens parts 11 shall be used so that the lens implant imitates the desired focal distance as close as possible.

[0030] In a preferred production method the lens implant is produced intraoccularly. Hereto, in the first step a small opening is cut into the lens capsule 2 and the lens body 3 is removed. This proceeds preferably by ultrasonics, laser technique, phacoemulsification or laserfakoemulsification. Corresponding methods are known to the person skilled in the art.

[0031] The distal part 11 of the lens is introduced thereafter into the lens capsule which has been hollowed accordingly. In order to allow the lens part 11 to be inserted even through such a small opening, it is elastically deformable so that they can be rolled up or folded and be inserted by means of a injection instrument. A instrument of this kind is disclosed e.g. in U.S. Pat. No. 5.620.450.

[0032] The distal part which has been inserted extends and roughly attains the desired position in the lens capsule. In a relaxed state it has a concave-concave curvature such as is disclosed in FIGS. 2 and 3. It forms the distal side of the lens implant and the shape of its convex surface 12 a corresponds to the one of the distal surface of the lens body to be replaced. Depending on what is required from the optical and mechanical properties, the distal part 11 can also be biconvex, i.e. its proximal surface can be bent towards the front or towards the back or be planar.

[0033] After the distal lens part has been positioned, the proximal lens part 10 is injected into the lens capsule 2 through a injection apparatus 13 in the form of a filling material in a flowable state and the lens capsule 2 is filled in its state accommodated to infinity. In this step, such an amount of filling material is injected that the volume of the lens implant corresponds substantially to the one of the previously removed lens body.

[0034] The lens capsule is, thereafter, closed and the proximal lens part 10 is cured to the desired rigidity, which can be achieved e.g. by a chemically, electrically or optically induced cross-linking. Suitable filling materials and techniques are known to the person skilled in the art e.g. from U.S. Pat. No. 4.608.050 or WO 89/00029.

[0035] A cross-linked polysiloxane, a hydrogel or a collagen-preparation can. e.g. be used as a filling material. Preferably, a gel is used because regarding it has a consistency similar to the lens body.

[0036] Arranging of the pre-fabricated lens part 11 at the distal side of the lens has the advantage that it forms a relatively stable rear wall for the lens. If a clouding occurs after the implanting at the distal area of the lens capsule 2, the lens capsule 2 can be removed in such this area by means of laser rays. The lens part 11 shields also without lens capsule 2 the possibly still flowable, physiologically less compatible first lens part 10 from the vitreous body of the eye and all other structures of the interior of the eye. Because opening of the rear capsule by a laser is never uniform, the softer material of the first lens part would otherwise leak out at the back because the capsule is subjected to pressure. This would destroy the optical function of the lens. Lens part 11 prevents such a leakage.

[0037] However, in particular if a more stable, physiologically well compatible material is used for the first lens part 10, the second lens part 11 can e.g. also be located in the center or in a proximal portion of the lens implant.

[0038] A second embodiment of the invention is illustrated in FIG. 4. Here the distal part consists of a bag 11 a which is filled by the transparent filling material 11 b. This structure has the advantage of producing a relatively large distal part 11 a, 11 b without that a large hole must be made in the lens capsule. After removing the lens body 3, the bag 11 a is first inserted in an empty, rolled state into the lens capsule. Thereafter a injection needle is inserted through the same opening. By means of the needle the filling material 11 b is fed into the bag 11 a. Finally, the proximal part 10 is filled in.

[0039] The bag 11 a is cut and pre-shaped in such a manner that it attains the desired shape in the filled state. In the kit mentioned above at least a part of the pre-shaped lens parts, in particular the larger ones thereof, may be provided as bags 11 a.

[0040] Subject of the present invention is a lens implant and a kit for the production of such lens implants. The invention relates, however, also to the above described, intraoccular method of production, in which the filling material for the first part 10 of the lens is introduced in a flowable state and a suitable lens part 11 is introduced in a solid state into the lens capsule 2. Preferably, the rigidity of the first lens part is thereafter increased by a curing. During this, the capsule should be accommodated to infinity.

[0041] Whereas in the present application preferred embodiments of the invention are described, it shall be clrearly understood that the invention is not limited thereto but can be also embodied otherwise within the scope of the following claims. 

1. Lens implant for placement into the lens capsule (2) and for replacing the lens body (3) of an eye, which has substantially the shape of the lens body (3) to be replaced, with a distal surface (12 a) and a proximal surface (12 b), wherein the distal surface (12 a) has a stronger curvature than the proximal surface (12 b), and with a first deformable part (10), characterized in that it comprises a second part (11) having a refractive index and/or an elastic deformability that differs from the one of the first part (10), which first part (10) forms a proximal portion and which second part (11) forms a distal portion of the lens implant.
 2. Lens implant of claim 1, characterized in that the second part has a refractive index which differs from the one of the first part (11).
 3. Lens implant of any of the preceding claims characterized in that the first part (10) and the second part (11) abut against each other.
 4. Lens implant of any of the preceding claims characterized in that the first part (10) is cureable intraoccularly from a flowable to a elastically deformable state.
 5. Lens implant of any of the preceding claims characterized in that the second part (11) is elastically deformable for introduction into the lens capsule in a rolled up or folded state.
 6. Lens implant of any of the preceding claims characterized in that the first part (10) forms the proximal surface (12 b).
 7. Lens implant of any of the preceding claims characterized in that a distal side of the second part (11) is curved in its relaxed state for forming the convex distal surface (12 a) of the lens implant.
 8. Lens implant of any of the preceding claims characterized in that the first part (10) includes at least a material selected from the group consisting of cross-linked polysiloxanes, hydrogels and collagen preparations.
 9. Lens implant of any of the preceding claims characterized in that the first part is better deformable that the second part, and in particular that the first part is better elastically deformable than the second part.
 10. Lens implant of any of the preceding claims characterized in that the first part is a gel.
 11. Lens implant of any of the preceding claims characterized in that the first part comprises a bag (11 a) filled by a filling material (11 b).
 12. Lens implant of any of the preceding claims characterized in that the proximal surface is convex with a radius of curvature between 8.4 and 13.8 mm, and in that the distal surface is convex with a radius of curvature between 4.6 and 7.5 mm, and in that the lens implant has a thickness between 2.8 and 5.5 mm.
 13. Lens implant of any of the preceding claims characterized in that it is dimensioned and shaped in such a manner that it has substantially the dimensions and shape of a natural lens body.
 14. Lens implant of claim 13, characterizes in that it is dimensioned and shaped in such a manner that it has substantially the dimensions and shape of a natural lens body accommodated to infinity.
 15. Lens implant of any of the preceding claims characterized in that the first part (10) has a volume that exceeds the volume of the second part (11).
 16. Lens implant of any of the preceding claims characterized in that the first part (10) has a diameter that exceeds the diameter of the second part (11).
 17. Kit for the production of lens implants of any of the preceding claims characterized by at least one flowable filling material for forming the first part (10), and a plurality of preshaped lens parts for a forming of the second part (11), which lens parts have differing shapes and/or refractive indices.
 18. Kit of claim 17, characterized in that the lens parts feature differing refractive indices.
 19. Kit of any of the claims 17 or 18, characterized in that the filling material is cureable from a flowable into a elastically deformable state.
 20. Kit of any of the claims 17 to 19, characterized in that at least a part of the lens parts consist of preshaped, fillable bags (11 a).
 21. Method of replacing the lens body of an eye by a lens implant, comprising the steps of removing the lens body from the lens capsule of the eye, introducing a solid, elastically deformable lens part (11) into the lens capsule (2) for the forming of a distal part of the lens implant and introducing a flowable filling material into the lens capsule at a proximal side of the deformable lens part (11) for the forming of a proximal part (10) of the lens implant.
 22. Method of claim 21 in which the flowable material is cured intraoccularly.
 23. Method of any of the claims 21 to 22 in which the eye is accommodated to infinity during the curing of the flowable filling material.
 24. Method of any of the claims 21 to 23, comprising the step of selecting the solid, elastically deformable lens part (11) out of a set of lens parts with various different refractive indices in accordance to a desired refractive index determined from properties of the eye.
 25. Method of any of the claims 21 to 24, characterized in that such a amount of the flowable filling material is introduced into the lens capsule that the lens implant has substantially the same volume as the removed lens body. 